Bookshelf Speaker Reviews

Price: $1,019 At A Glance: Time Lens time-aligns tweeter and woofer • Acoustic Lens controls tweeter response • Wireless sub eliminates interconnect cable

Through a Lens, Blackly

Compact satellite/subwoofer sets were once surround’s entry-level configuration, a smart option for those who wanted to go beyond two-channel in a small room. More recently, they’ve ended up in the middle ranks of the home theater hierarchy—below monitor-class and floorstanding speakers but above the relatively new soundbar category and built-in HDTV speakers.

Why do compact sat/sub sets rank below larger stand-mount and floorstanding speakers? Because the tiny satellites produce little bass of their own. With chunkier stand-mount speakers running at a sub crossover of, say, 80 hertz, the speakers and sub divide bass-production duties at a lower frequency. This results in a more natural distribution of upper bass and midbass. It breaks their perceived location out of the sub and spreads them around the soundfield to where their matching higher frequencies are coming from. But compact sat/sub sets usually operate at a higher crossover, about 100 to 150 Hz or higher. This either expands the sub’s workload and makes it noticeable that more midbass frequencies are coming from only one place; or it results in a hole in the midbass between the sub’s upper range and the satellite’s lower range.

Why do I believe sat/sub sets rank above soundbars? Let’s assume that a sat/sub set and a soundbar have drivers of the same size and quality. The sat/sub set will potentially provide a wider front soundstage because you can place the speakers farther apart.

Why do sat/sub sets rank above HDTV speakers? If you even have to ask this question, especially now that a flat-panel bezel is as thin as a pencil, you should have your ears examined. I can’t even take in the evening news on the back-facing speakers built into my HDTV. All I hear is mush.

You shouldn’t expect the Polk Blackstone sat/sub set to provide slammin’ all-channel midbass localization and heft. But you may expect it to distribute midrange and high frequencies around the room. In my opinion, this system does this well, thanks to its matched satellites in all four corners of the soundfield. As an added benefit in this system, the sub is wireless. You’ll need to find a power outlet for it, but you won’t have to run an interconnect cable from your A/V receiver to the sub.

The Blackstone system reviewed here consists of the TL250 5-Pack ($500), DSW PRO 440 wi wireless subwoofer ($400), and PWSK-1 wireless sub kit ($119), totaling $1,019. TL250 is basically the TL2 satellite (sold separately for $100 each) times four plus the TL2 Center (sold separately for $125). The TL2 has a 0.75-inch silk-dome tweeter and a 3.25-inch mineral-filled polypropylene woofer.

Let’s note in passing that the smaller TL1 satellite has smaller drivers, including a 0.5-inch silk polymer tweeter and a 2.5-inch composite woofer. You can buy it in a 5.1-channel set as the TL2600 ($750). Interestingly, while the TL3 has the same driver sizes as the TL2, the TL3 drivers differ in other ways, borrowing the ring-radiator tweeter from Polk’s LSi Series. I reviewed the LSi7 for another publication many years ago, and it was one of the best speakers I’d ever heard up to that time.

TL Stands for Time Lens
The TL in these various model numbers stands for Time Lens. This is how Polk describes the placement of the drivers in these speakers. The acoustical center of the tweeter and woofer are located in the same spatial plane for what Polk claims is better imaging. A tweeter recess or “acoustic lens” is molded into the grille frame, which is said to smooth the driver’s frequency response. When I popped off the grilles, I noticed that the edges of the TL2 Center’s lens were sharper than those of the TL2 satellite.

Polk sculpted the TL Series enclosures with particular verve. With the grilles on, the top front of the baffle is lopped off in a flat plane. With the grilles off, the tweeter angling remains, but the curve is softer. The sides, and even the back, are also curved, which helps defeat unwanted panel resonances and internal standing waves from parallel walls. The speaker leans back against a nonremovable wedge-shaped pedestal that incorporates the port.

Blackstone’s black gloss plastic finish is intended to complement the current fashion in flat-panel HDTVs. To look at it, you wouldn’t suspect that a steel plate lies beneath it, making the enclosure stronger and more acoustically inert. That’s always a good thing. Several knuckle raps showed that the enclosure was the least lively at the sides of the baffle and along the top. Mounting options consist of a keyhole mount and a 0.25-inch by 20 threaded insert—and the two are combined, with the insert lying inside the keyhole. Ingenious.